An increasing number of Latino children in the US speak primarily Spanish in the home, and have minimal proficiency in English when they enter school. Because many of these emerging bilingual children are from lower-SES backgrounds, they are at increased risk for poor academic outcomes. The strongest single correlate of later success in school is a child?s oral language skills achieved before kindergarten. A question with critical public policy and educational implications is how family learning environments in a first language (L1) contribute to shaping language processing skills that could impact learning in the second language (L2). Our extensive work examining individual differences in the efficiency with which young children understand spoken language in real time has shown that early language processing efficiency is strongly linked to outcomes within a given language, but also that benefits extend to vital academically relevant skills such as working memory. Moreover, features of children?s early caregiver-child interactions shape the development of this critical information processing skill. Here, we seek to extend this important research program to emerging Spanish- English bilinguals, a rapidly growing and highly vulnerable population in the US. The two longitudinal studies proposed here offer the unique opportunity to explore both precursors and long-term consequences of having a strong foundation in early language processing skills in Spanish, asking whether early L1 processing skills support later language, cognitive, literacy and executive function (EF) skills in school. In Study I, children from our previous studies who participated in the LWL task at 2 years will be tested on a comprehensive battery of standardized tests at 5, 6 and 7 years (n=90). To what extent does individual variation in 2-year Spanish processing efficiency predict both later outcomes in Spanish and growth in emerging spoken or written skills in English? Does variation in early Spanish processing also link to later skills that support learning independent of language, such as EF, working memory, and reasoning? In Study II, Latino children (n=100) from monolingual Spanish-speaking families participate in the LWL task at 2 years and in assessments of language, cognitive, EF and pre-literacy skills at 2, 3 and 4.5 yrs. We also examine features of learning environments that support the development of language processing skills using laboratory play sessions and day-long naturalistic recordings. Embracing the heterogeneity of learning experiences in this population, we trace trajectories of exposure to English and delineate the quantity and quality of in-home and outside-the-home experiences which may moderate relations between early processing efficiency and later outcomes. We propose a model of cumulative risk such that late emerging bilinguals with less supportive learning environments are at the greatest disadvantage due to a weak foundation in language processing skill and later exposure to English. These studies address a critical gap in the literature and will have broad-reaching implications for adjusting early education policy to most effectively support learning in this growing and at-risk population.